I recently read the book Boundaries by Anne Katherine (https://www.amazon.com/Boundaries-Where-Begin-Recognize-Heal...) and feel like it was exceptionally eye opening. I always felt like I had a normal-ish upbringing (but how do you ever really know, outside of egregious abuse?) but there was very little to no modeling of positive boundaries and individuation, and it has negatively impacted my relationships.
I've also read some of Henry Cloud's "Boundaries" book, but it was a little too Bible-oriented for me, but that may not bother you. His writing is very clear and he had many insightful gems sprinkled throughout the heavy reference to scripture.
It also may be worth talking to a therapist or counselor (and I would suggest doing it just for yourself first) before trying marriage / couples counseling. In my experience with marriage counselors (admittedly not a lot), the relationship itself is effectively the client. The one I went to wouldn't even discuss with us that our marriage may not be right for either of us whereas a personal therapist is there specifically for you.
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